1. Field of the Invention
The present invention relates to a method of manufacturing a metal oxide semiconductor transistor and a complementary metal oxide semiconductor transistor, an more particularly, to a method of manufacturing a metal oxide semiconductor transistor and a complementary metal oxide semiconductor transistor, which forms source/drain extension areas before forming epitaxial layers.
2. Description of the Prior Art
Since the sizes of semiconductor components get smaller and smaller, the processes of manufacturing the transistors have improved greatly in forming small size and high quality transistors.
The method of manufacturing the prior transistor involves first forming a gate, and then a low thermal budget ion implanting process is used to form source and drain extension areas (also called lightly doped drain, LDD) in the silicon substrate and on the two sides of the gate. A spacer is formed besides the gate, and the gate and the spacer serve as a mask for another ion implanting process, so as to form the source/drain. A plurality of contact plugs are formed in order to electrically connect the gate, the source, and the drain of the transistor. The surfaces of the gate and source/drain are formed with silicide by the self-aligned suicide process to improve the Ohmic contact among the gate and the source/drain.
However, the metal in the metal layer expands into the silicon substrate and consumes the silicon in the source/drain in the self-aligned silicide process. The original crystal lattice of the source/drain is damaged, and the PN junction between the source/drain and the silicon substrate is too narrow, so as to generate leakage. The components lose efficacy in the ultra shallow junction (USL).
A better solution is utilizing the selective epitaxial growth (SEG) process to stand the source/drain high, so that the silicide and the silicon substrate don't contact directly, and the source/drain extension areas are maintained. But, the temperature of the SEG process is 690 to 790 centigrade, which causes the source/drain extension areas to be damaged. So, researching methods of manufacturing the source/drain extension areas and the epitaxial layers at the same time is important.